Yamaha XP-7000 Service Manual page 38

XP7000/XP5000
3.10 Stability
Use only the polyester film capacitor of net capacity of 0.01 uF as a load.
Input the 1 kHz, -10 dBu rectangular square wave and check that no oscillation occurs and following conditions are satisfied.
Overshoot
Ringing
3.11 Protection circuit
Disconnect the load resistance from the output terminal.
Short-circuit 2 jumper cables within the "DC-C" marked frame of the PS circuit board and check that the power is shut down
within 2 seconds.
After checking, make short-circuited jumper cables off. Turn off the power and turn it on again 3 seconds later to check that the
unit can be restarted normally.
3.12 Efficiency
(1) Input a 1 kHz, -6.6 dBu signal and measure the primary power.
Check that the measured value is within the range specified in the table below.
XP7000
140 +/- 30 W
(2) Shunt 2 pin (hot) and 3 pin (cold) of input terminals with 600 ohms and measure the primary power. Check that the
measured value is within the range specified in the table below.
XP7000
35 +/- 10 W
3.13 VI limiter and comp.
Connect 1 ohms (± 5%) load to the output terminal and input a 1 kHz, -1.5 dBu signal. Check that the output voltage is within
the range specified in the table below. Also check that the distortion is 5% or less and the CLIP LED lights up.
Perform this inspection on each channel separately.
This inspection should be completed within 30 seconds.
XP7000
18 +/- 4 V
3.14 SIGNAL LED
Input a 1 kHz, -23 dBu sine wave signal and check that the SIGNAL LED lights up. Perform this inspection on each channel
separately.
38
: Vp/Vo<2.5
: Converged within 7 waves and no oscillation generated
XP5000
140 +/- 30 W
XP5000
35 +/- 10 W
XP5000
16 +/- 4 V
Vp
Vo
··· Ringing Waves